Radiation Oncology/Medulloblastoma/Staging

Medulloblastoma Staging

Modified Chang's Staging

T Stage

• T1 - tumor <3 cm in diameter
• T2 - tumor ≥3 cm in diameter
• T3a - tumor >3 cm and with extension into Aqueduct of Sylvius or foramen of Luschka
• T3b - tumor >3 cm and with unequivocal extension into brainstem
• T4 - tumor >3 cm with extension past Aqueduct of Sylvius or down past foramen magnum

M Stage

• M0 - No evidence of gross subarachnoid or hematogenous metastasis
• M1 - microscopic tumors cells found in CSF
• M2 - gross nodular seeding intracranially beyond the primary site (in cerebellar/cerebral subarachnoid space or in third or lateral ventricle)
• M3 - gross nodular seeding in spinal subarachnoid space
• M4 - metastasis outside cerebrospinal axis

Risk Stratification

• Standard (Average) Risk (66%)
  • >3 years old
  • <1.5 cm² residual disease after resection
  • M0 by craniospinal MRI and CSF
• High Risk (34%)
  • <3 years old
  • Subtotal resection, >1.5 cm² residual tumor
  • M+; leptomeningeal seeding
  • Location outside of posterior fossa (PNET)